{% if page.extra.series %}
{% set section_data = get_section(path="posts/_index.md") %}
{% set_global series_pages = [] %}
{% for p in section_data.pages %}
  {% if p.extra.series and p.extra.series == page.extra.series %}
    {% set_global series_pages = series_pages | concat(with=p) %}
  {% endif %}
{% endfor %}
{% set series_sorted = series_pages | sort(attribute="extra.series_index") %}
{% set series_total = series_sorted | length %}

<div class="series-nav" aria-label="Post series: {{ page.extra.series }}">
  <div class="series-nav-header">
    <span class="series-nav-eyebrow">Series</span>
    <span class="series-nav-title">{{ page.extra.series }}</span>
    <span class="series-nav-badge">{{ page.extra.series_index }} / {{ series_total }}</span>
  </div>
  <ol class="series-nav-list">
    {% for p in series_sorted %}
    <li class="series-nav-item{% if p.permalink == page.permalink %} is-current{% endif %}">
      <span class="series-nav-index">{{ p.extra.series_index }}</span>
      {% if p.permalink == page.permalink %}
      <span class="series-nav-label" aria-current="page">{{ p.title }}</span>
      {% else %}
      <a class="series-nav-label" href="{{ p.permalink }}">{{ p.title }}</a>
      {% endif %}
    </li>
    {% endfor %}
  </ol>
</div>
{% endif %}